Pre-dosing antibody levels and efficacy of thrombolytic drugs containing streptokinase

Synthesis and Bioactivities of Marine Pyran-Isoindolone Derivatives as Potential Antithrombotic Agents

2,5-Bis-[8-(4,8-dimethyl-nona-3,7-dienyl)-5,7-dihydroxy-8-methyl-3-keto-1,2,7,8-teraahydro-6H-pyran[a]isoindol-2-yl]-pentanoic acid (FGFC1) is a marine pyran-isoindolone derivative isolated from a rare marine microorganism Stachybotrys longispora FG216, which showed moderate antithrombotic(fibrinolytic) activity. To further enhance its antithrombotic effect, a series of new FGFC1 derivatives (F1-F7) were synthesized via chemical modification at C-2 and C-2' phenol groups moieties and C-1″ carboxyl group. Their fibrinolytic activities in vitro were evaluated. Among the derivatives, F1-F4 and F6 showed significant fibrinolytic activities with EC50 of 59.7, 87.1, 66.6, 82.8, and 42.3 μM, respectively, via enhancement of urokinase activity. Notably, derivative F6 presented the most remarkable fibrinolytic activity (2.72-fold than that of FGFC1). Furthermore, the cytotoxicity of derivative F6 was tested as well as expression of Fas/Apo-1 and IL-1 on HeLa cells. The results showed that, compared to FGFC1, derivative F6 possessed moderate cytotoxicity and apoptotic effect on HeLa cells (statistical significance p > 0.1), making F6 a potential antithrombotic agent towards clinical application.

Delivery of tissue plasminogen activator and streptokinase magnetic nanoparticles to target vascular diseases

Thrombolytic therapy for acute myocardial infarction standardly makes use of the medications streptokinase (SK) and tissue plasminogen activator (tPA). In this study, the potential of silica-coated magnetic nanoparticles (SiO2-MNPs) as nanocarriers clinical thrombolytic therapy was investigated. SiO2-MNPs for use in targeted therapeutic delivery of tPA and SK were prepared using a combined technique incorporating controlled precipitation and hydrothermal methods. Response surface methodology (RSM) was employed to evaluate the efficiency of the SiO2-MNPs. The production of SK secreted from Streptococcus equi was enhanced using random mutagenesis. The tPA and SK A were encapsulated by means of a silanizing agent with a surface rich in 3-aminopropyltrimethoxysilane layered around the SiO2-MNPs. Blood clot lysis assays and fibrin-containing agarose plates were used to carry out in vitro thrombolysis testing. The optimum conditions for producing MNPs were found to be at pH=13 and at a temperature of 75°C for 45 min. Culture conditions of 2.75% NaCl concentration at initial pH=7.5 for 90 s under UV resulted in maximum SK activity. The tPA/SK-conjugated SiO2-MNPs (SiO2-MNP-tPA-SK) increased operating stability in whole blood and storage stability in a buffer by 92%. More effective thrombolysis using magnetic targeting was indicated by a 38% reduction in blood clot lysis time achieved with SiO2-MNP-tPA-SK compared to administering the SiO2-MNPs without guidance. The silica-coated magnetic nanocarriers developed in this study show potential for improved clinical thrombolytic therapy.

Antistreptokinase antibodies and outcome of fibrinolytic therapy with streptokinase for left-sided prosthetic valve thrombosis

BACKGROUND

Left-sided prosthetic valve thrombosis (PVT) is a serious complication of valve replacement. In developing countries, fibrinolysis with streptokinase (SK) is often used as the first line of treatment. Anti-streptokinase (anti-SK) antibodies are widely prevalent in the general population, but their effect on the efficacy and outcome of fibrinolysis with SK in patients with PVT is not known.

METHODS

Patients with rheumatic heart disease and prosthetic valve replacement presenting with a first episode of left-sided PVT were enrolled. All patients underwent fibrinolysis with SK. An indirect enzyme-linked immunosorbent assay was used to detect anti-SK antibodies before fibrinolysis. Relationship of these antibodies to the outcome of fibrinolysis was evaluated.

RESULTS

Forty-four patients treated for left-sided PVT were included. Thrombosis affected 33 mitral and 11 aortic prosthetic valves. On fibrinolysis with SK, 32 (73%) patients achieved complete success, whereas it was unsuccessful in the remaining 12 patients. There were 3 bleeding events, 1 stroke, and 3 deaths. Mean anti-SK antibody levels were not significantly different between patients who had complete success and those who did not (8.81 ± 2.43 vs 7.67 ± 1.26 Au/mL; P = .13) and did not correlate with the outcome after adjustment with other variables. Patients in New York Heart Association class III or IV had a greater chance of failed fibrinolytic therapy, even after adjustment for other prognostic variables (odds ratio 9.0; 95% CI 1.29-63.02; P = .027).

CONCLUSION

Anti-SK antibody titers are not associated with success of fibrinolytic therapy using SK in patients with left-sided PVT.

Antistreptokinase antibodies: implications for thrombolysis in a region with endemic streptococcal infection

AIMS

To determine antistreptokinase antibody (anti-SK) titres in patients with the acute coronary syndrome from communities with endemic group A streptococcal infection because of the implications for streptokinase (SK) thrombolysis.

METHODS

Anti-SK titres were determined using a standard method in 47 consecutive SK naive patients, presenting to the Mt Isa Hospital emergency department, Australia, with an acute coronary syndrome. Both indigenous and non-indigenous subjects were enrolled. Antistreptolysin O (ASOT) and anti-DNAse B (ADB) titres were also determined.

RESULTS

Indigenous patients were more likely to have anti-SK antibodies (p < 0.001) than the non-indigenous cohort. Anti-SK antibody titres also correlated well with ASOT/ADB titres.

CONCLUSIONS

Anti-SK antibodies are highly prevalent in SK naive indigenous patients presenting with the acute coronary syndrome. Streptokinase should not be used for thrombolysis in populations with endemic group A streptococcal infection.

Inhibition of Streptokinase-Induced, Antibody-Mediated Platelet Aggregation with Tirofiban After Exposure to Streptokinase or Streptococcal Infection

STUDY OBJECTIVE

To evaluate the effect of tirofiban (a glycoprotein IIb-IIIa inhibitor) in preventing streptokinase-induced, antibody-mediated platelet aggregation after administration of streptokinase or development of a streptococcal infection.

DESIGN

Prospective analysis.

SETTING

Research center of a Canadian hospital.

PARTICIPANTS

Forty-five healthy volunteers, 45 patients who had received streptokinase within the past 3 years, and 13 patients who had a severe streptococcal infection also within the past 3 years.

INTERVENTION

Blood samples were drawn to measure the extent of inhibition of streptokinase-induced, antibody-mediated platelet activation and aggregation by tirofiban.

MEASUREMENTS AND MAIN RESULTS

Platelet aggregation was measured by using a turbidimetric method. The extent of inhibition by tirofiban was measured by incubating tirofiban for 2 minutes before adding streptokinase 5000 U/ml. Also, tirofiban was added 2 minutes before adding adenosine 5'-diphosphate (ADP) 2 microM/L into the last tube as a comparison. Strepto-kinase-induced, antibody-mediated platelet aggregation was observed in 10 (22%) of the 45 patients treated with streptokinase, in 3 (23%) of the 13 patients with streptococcal infection, and in none of the 45 healthy volunteers. Tirofiban inhibited streptokinase-induced, antibody-mediated platelet aggregation by 89 +/- 14% (p<0.001). Similarly, ADP-induced platelet aggregation was inhibited by 92 +/- 6% (p<0.001) with tirofiban.

CONCLUSION

Streptokinase-induced, antibody-mediated platelet aggregation occurred in 13 (22%) of 58 patients who received streptokinase or were exposed to a streptococcal infection in the past 3 years. Such patients may not benefit from streptokinase therapy. In these patients, tirofiban significantly decreased the extent of antistreptokinase antibody-mediated platelet aggregation. Hence, patients undergoing streptokinase therapy may benefit from tirofiban as adjunctive therapy.

Antistreptokinase platelet-activating antibodies are common and heterogeneous

BACKGROUND

Platelet activation by antistreptokinase (SK) antibodies could impair the clinical effect of SK administration.

OBJECTIVE

To better describe anti-SK antibodies with particular emphasis on procoagulant activities as a result of platelet activation.

PATIENTS AND METHODS

Sera were collected from 146 patients with coronary artery disease: non-SK-treated, 95 from mainland France, 31 from French Polynesia; 20 patients from mainland in year 2 after SK treatment. Serum-induced SK-dependent platelet activation resulting in procoagulant activities was assessed with washed platelets from five donors representative of the known patterns of reactivities to IgG.

RESULTS

Concentrations (2-5252 microg mL(-1)) and fibrinolytic neutralization titres (< 10 to > 1280) were found in the expected wide range and correlated (rho = 0.66, P < 0.0001). Platelet activation was detected with 145 samples, but varied in intensity and pattern (depending on the donors), although there was no systematic hierarchy; it was presumably due to IgG (inhibited by an IgG Fc receptor-blocking antibody and recovered in the IgG fraction) and only partially affected by aspirin. Marked platelet activation could be detected in samples with concentration as low as 2 microg mL(-1), and/or no detectable neutralizing titers. The way of immunization to SK was not found to influence the functional profile of antibodies.

CONCLUSION

Anti-SK platelet-activating antibodies are widespread, heterogeneous, poorly predictable on the basis of their antifibrinolytic effect and strong enough to trigger procoagulant activities. Their clinical relevance should be formally assessed, using patients' own platelets for detection owing to the variation of platelet reactivity.

Effect of intrapleural streptokinase administration on antistreptokinase antibody level in patients with loculated pleural effusions

BACKGROUND

Streptokinase is widely used IV for the treatment of myocardial infarction and intrapleurally for the treatment of loculated pleural effusions. IV administration of streptokinase is known to cause the production of antistreptokinase antibodies.

OBJECTIVE

The aim of this study was to evaluate whether the intrapleural administration of streptokinase results in a similar elevation of the serum antistreptokinase antibody level.

METHODS

During 1 year, venous blood samples were taken from 16 consecutive patients (10 men and 6 women; age range, 22 to 60 years) requiring intrapleural streptokinase administration (250,000 IU once a day, for 2 to 6 days). Blood samples were taken before treatment, on day 5, and day 14. Antistreptokinase antibodies were measured using enzyme-linked immunosorbent assay (ELISA) and were expressed in arbitrary ELISA units. Four patients with myocardial infarction treated with IV streptokinase (1,500,000 IU) were included as control subjects for the method.

RESULTS

Before treatment, the median antistreptokinase antibody level in patients with loculated pleural effusions was 729 ELISA units (range, 196 to 13,529 ELISA units) and increased to 9,240 ELISA units (range, 1,456 to 77,389 ELISA units) by day 14 (p < 0.0001). In the control group, the median pretreatment level was 119 ELISA units, and by day 14 it had increased to 20,495 ELISA units. Four patients who developed an elevated body temperature after intrapleural administration of streptokinase had a significantly higher pretreatment antistreptokinase antibody level compared to other patients.

CONCLUSIONS

The intrapleural administration of streptokinase results in the elevation of the serum antistreptokinase antibody level, which is similar to the case with IV administration. An increased pretreatment antistreptokinase antibody level does not influence the result of intrapleural fibrinolysis but can cause an elevation of body temperature after the administration of streptokinase.

Platelet activity and antibody titers after exposure to streptokinase or streptococcal infection

INTRODUCTION

Streptokinase use, in acute myocardial infarction, is hindered by failure to reperfuse (60%) and early reocclusion (16%). This phenomenon may, among other causes, be due to systemic inactivation of streptokinase, as well as streptokinase-induced platelet aggregation and clot propagation from antibodies to streptokinase produced after streptokinase administration or streptococcal infections. The purpose of this study was to determine the incidence of streptokinase-induced, antibody-mediated, platelet activation and aggregation after administration of SK or development of a streptococcal infection.

MATERIALS AND METHODS

We included 45 normal volunteers (Control group), as well as 45 patients who had received streptokinase (Streptokinase group) and 13 who had suffered a severe streptococcal infection (Streptococcal infection group) within the past 3 years. Extent of streptokinase-induced, antibody-mediated, platelet activation and aggregation, as well as anti-streptokinase antibody and streptokinase resistance titers (lowest streptokinase concentration to cause clot lysis within 10 min) were measured.

RESULTS

Whereas streptokinase-induced, antibody-mediated, platelet activation was observed in 49% of streptokinase patients and in only 17% and 15% of streptococcal infection patients and normal volunteers (p<0.05 Streptokinase vs. Control and Streptokinase vs. Streptococcal infection), streptokinase-induced platelet aggregation was observed in 23% of streptokinase patients and streptococcal infection patients, and in none of the control patients (p<0.05).

CONCLUSIONS

Streptokinase-induced, antibody-mediated, platelet activation and aggregation occur in patients with high titers of anti-streptokinase antibody and may play a role in failure of streptokinase therapy. Streptococcal infection patients behave like streptokinase patients in terms of the reactivity of their platelets to subsequent streptokinase dose in vitro.

The effect of streptokinase neutralizing antibodies on fibrinolytic activity and reperfusion following streptokinase treatment in acute myocardial infarction

OBJECTIVES

To evaluate tissue plasminogen activator (tPA) activity as a measure of fibrinolytic response to treatment with streptokinase (SK) and to relate this to the effect of pretreatment SK antibodies and to successful reperfusion assessed by continuous computerized vectorcardiography (VCG).

SETTING

Umeå University Hospital.

SUBJECTS

A total of 104 patients with acute myocardial infarction (AMI) treated with SK and no history of previous SK treatment were studied. The tPA activity was measured 4 h after the start of treatment. The effect of pre-existing neutralizing antibodies to SK was analysed with a functional assay in pretreatment samples. Reperfusion was evaluated with VCG.

MAIN OUTCOME MEASURES

Successful reperfusion.

RESULTS

Fifty-five patients (53%) were classified as successfully reperfused. The risk for failed reperfusion was calculated in logistic regression models. In a univariate model, a borderline significant increase in the risk of failed reperfusion was observed in intermediate levels of SK neutralizing antibodies, but not in the highest levels. In a multivariate model, only high tPA activity, >25 U mL(-1), at 4 h (OR 0.17: 95% CI: 0.06-0.51) was associated with a higher rate of reperfusion whilst longer time to treatment (OR 1.17; 95% CI: 1.02-1.35) was associated with a higher risk of failed reperfusion. There was no significant correlation between neutralizing antibodies to SK and tPA activity at 4 h.

CONCLUSION

The SK treatment of AMI induced high levels of tPA activity which were associated with successful reperfusion. The effect of pre-existing SK antibodies had no significant influence on reperfusion and were not correlated to the fibrinolytic activity obtained.

Streptokinase antibodies inhibit reperfusion during thrombolytic therapy with streptokinase in acute myocardial infarction

OBJECTIVES

To evaluate the influence of pretreatment IgG against streptokinase on the outcome of streptokinase treatment in acute myocardial infarction.

SETTING

Coronary care unit.

DESIGN

From 88 patients admitted to the coronary care unit due to chest pain, blood samples were taken for determination of the pre-existing titre of antibodies against streptokinase. The patients were treated and monitored according to standard protocols. Fifty of the patients received thrombolytic therapy with streptokinase due to acute myocardial infarction and were monitored with continuous dynamic vectorcardiography, making possible the continuous analysis of ST- and QRS-vector changes and determination of the event of reperfusion. None of these 50 patients had been given streptokinase therapy previously.

RESULTS

According to the vectorcardiographic criteria 21(42%) patients had signs of early (within 2 h) reperfusion after streptokinase therapy. These patients had lower pre-existing antibody titres than patients without signs of reperfusion (mean values 0.20 and 0.45 arbitrary units, P = 0.01). None of the patients with a titre higher than 0.50 arbitrary units (nine patients) had signs of early reperfusion. Of the 41 patients with a titre lower than 0.50 arbitrary units 52.5% had signs of early reperfusion.

CONCLUSION

The present investigation indicates that pre-existing streptokinase antibodies play an important role in reperfusion failure during thrombolytic therapy with streptokinase in acute myocardial infarction. Therefore, the determination of streptokinase antibodies may differentiate between those patients who may benefit from streptokinase treatment and those who should be treated with some other regime.

Incidence and impact on outcome of streptokinase allergy in the GUSTO-I trial. Global Utilization of Streptokinase and t-PA in Occluded Coronary Arteries

We evaluated allergic reactions in 20,201 patients randomized to the streptokinase arms of The Global Utilization of Streptokinase and t-PA (Tissue Plasminogen Activator) in Occluded Coronary Arteries (GUSTO-I) trial, and tested the hypothesis that patients with streptokinase allergy would exhibit higher mortality. After adjusting for baseline variables and time of death, we found comparable coronary patency, left ventricular function, mortality, and bleeding complications between patients with versus those without streptokinase allergy.

Systemic lytic state is not a predictor of coronary reperfusion in acute myocardial infarction

To investigate why approximately one third of patients thrombolysed with streptokinase fail to reperfuse, we assessed the lytic status, antistreptokinase antibody and non invasive parameters of reperfusion in 95 consecutive patients with acute myocardial infarction treated with streptokinase for the first time. The lytic status was assessed by Clauss fibrinogen assay and thrombin clotting time before and 2 h after streptokinase infusion. Antistreptokinase antibody was measured prior to the infusion. Reperfusion was assessed by measurement of the 24:96 h troponin-T ratio (a ratio > 1 indicating reperfusion) and ST segment resolution 2 h post streptokinase. Ninety-two (97%) patients achieved a systemic lytic state with a fibrinogen titre of less than 1.0 g/l and thrombin clotting time ratio of > 2.5. Despite this, 27% failed to reperfuse with a mean 24:96 h troponin-T of 0.9, SD 0.6 vs. 3.4 +/- 3.2 in the reperfused group, (P < 0.0001). 83% of the reperfused group but none of the non reperfused group had ST segment resolution. No difference was observed in the levels of fibrinogen and thrombin clotting time between the reperfused 0.25 +/- 0.3 g/l; 6.9 +/- 4, and the non reperfused group 0.4 +/- 0.6 g/l; 7.9 +/- 2.6. No difference was observed in the levels of antistreptokinase antibody between the reperfused (median = 168 U/ml and the non reperfused (median = 177 U/ml). Failure to reperfuse with Streptokinase is not due to failure to achieve a lytic state. Therefore increased or accelerated dosages of streptokinase are unlikely to increase the rate of reperfusion.

Pulmonary embolism--the role of thrombolytic therapy in its management

In massive pulmonary embolism where there may be evidence of right ventricular dysfunction and acute pulmonary hypertension, anticoagulation therapy alone may prove inadequate. In such situations use of thrombolytic agents produces an improvement in haemodynamics compared to anticoagulants alone, although studies to date have been too small to address the issue of mortality benefit. It would appear that all age groups gain benefit from the use of thrombolytics. Studies that have compared thrombolytic agents and anticoagulants are discussed. In addition, the issues of the choice of thrombolytic agent and the different modes of delivery of therapy are addressed.

Anti-streptokinase antibodies and streptokinase resistance in an Aboriginal population in northern Australia

BACKGROUND

Thrombolytic treatment with streptokinase in acute myocardial infarction has proven to be safe and effective in Caucasian populations with relatively low levels of anti-streptokinase IgG and streptokinase resistance. Higher levels of antibodies, as seen in previous recipients of streptokinase therapy, cause more adverse reactions and may result in lower efficacy.

AIMS

To examine the levels of anti-streptokinase IgG and streptokinase resistance in a population subjected to endemic streptococcal infections.

METHODS AND RESULTS

Thirty Aboriginal adults from a remote community in Northern Australia with endemic streptococcal infections and 15 non-Aboriginal adults from an urban community without endemic infections participated in this study. Aboriginal adults exhibited levels of anti-streptokinase IgG and streptokinase resistance that, respectively, were almost 20 and 15 times greater than the values of non-Aboriginal adults. At least 23% of Aboriginal adults had sufficiently high levels of streptokinase resistance to neutralise a standard 1.5 million unit dose of streptokinase.

CONCLUSIONS

Aboriginal adults from a remote community had dramatically elevated levels of anti-streptokinase IgG and in vitro streptokinase resistance. Prospective studies are needed to assess the clinical relevance of streptokinase resistance in populations from areas with endemic streptococcal infection.

How safe is the readministration of streptokinase?

Streptokinase is an antigenic thrombolytic agent used for the treatment of acute myocardial infarction. It reduces mortality as effectively as the nonantigenic alteplase in most infarct patients while having the advantage of being much less expensive. This cost implication is important since myocardial reinfarction is common, with fibrinolytic therapy indicated in many patients with reinfarction. Following streptokinase, antistreptokinase antibodies and neutralisation titres can rise to significant levels from 4 days after the initial dose. These antibodies can presist for at least 4 years in up to 50% of patients. It is possible that these antibodies may cause allergic reactions or neutralisation of a further dose of streptokinase, rendering it ineffective for the treatment of myocardial reinfarction. To date, 2 small studies of patients without previous streptokinase exposure suggest that higher antibody titres are associated with a lower rate of coronary reperfusion, while a further study suggests that high titres are associated with hypersensitivity reactions. At present the readministration of streptokinase cannot be recommended from 4 days after a first dose. Further larger studies are needed to assess the effect of high neutralisation titres on coronary reperfusion.

Does the potential for development of streptokinase antibodies change the risk-benefit ratio in older patients?

In patients with acute myocardial infarction (MI), quick initiation of thrombolytic therapy is the best strategy for improvement of survival and reduction of morbidity. Streptokinase, a purified product of haemolytic streptococci, is the most commonly administered agent. The compound anistreplase (a complex of streptokinase to plasminogen), is available but currently not often used. The non-antigenic competitor for these two compounds for the indication of MI is alteplase (recombinant tissue plasminogen activator, rt-PA). Due to former use of streptokinase or its derivative anistreplase, patients may develop specific antibodies to the foreign protein, whereas cross-reacting antibodies may be due to streptococcal infections. These antibodies may neutralise streptokinase or its derivative in case of (re)administration and may mediate adverse events, sometimes serious. Since advanced age by itself is certainly not a contraindication to thrombolytic therapy, and because reinfarction occurs frequently, the benefit-risk ratio of re-exposure to streptokinase or its derivative is decreased in the elderly who present with reinfarction. In the framework of tailored thrombolytic therapy, alteplase or urokinase appear to be the drugs of choice in these patients.

Criteria for drug usage review of thrombolytics in acute myocardial infarction

Thrombolytic drugs are now the mainstay of the management of acute myocardial infarction (AMI). Although their use is associated with reduced mortality, significant adverse effects can occur, especially if they are used inappropriately. Drug usage review of this group of drugs provides a measure of the appropriateness of their use. The development of criteria against which the use of these drugs can be compared allows the collection of qualitative and quantitative data on their use. Those criteria identified during this process include: evidence for, and accuracy of, diagnosis of AMI; when, where and how to administer the drug; what drug to use, and at what dose. Identification of potential adverse effects, measures of treatment success and the role of adjunctive therapy may also be included as part of a drug usage evaluation process.